MinarcMig Parts FAQs
Straight answers to the questions people ask most when buying spare parts for a compact MIG welding machine and its torch.
How do I know when to change the contact tip?
Change it when the arc becomes unstable or erratic, when the hole in the tip has worn out of round, or when the tip is burned or deformed. As the hole enlarges, electrical contact with the wire becomes inconsistent, which shows up as an unsteady arc.
If the wire has burned back and fused to the tip, replace the tip rather than reuse it, and look for the cause, such as a wrong-size tip, a restricted liner or a poor earth connection. There is no fixed interval, because it depends on the wire, the current and how long you weld.
Does the contact tip size matter?
Yes. The hole must match the diameter of the wire you are using, with only a very small clearance so the wire can slide freely while still making good electrical contact. An oversized hole lets the wire move about, causes arcing inside the tip and is a common cause of burnback, so a bigger tip is not a cure for feeding problems.
For aluminium wire, use tips made for that wire. Check the wire size on the spool and the size marked on the tip when you order.
What is the difference between a standard gas nozzle and a thick-wall or heavy-duty one?
The nozzle directs the shielding gas over the weld pool. A heavier, thicker-walled nozzle usually stands up better to the heat and spatter of longer or higher-current welding, and is often chosen for heavy-duty work and for aluminium. A standard nozzle is fine for general, lighter work.
To get good shielding the nozzle must be large enough to cover the weld pool, clean, and undamaged. Spatter build-up or damage can cause patchy gas cover and porosity, so clean or replace the nozzle when it clogs.
Why does the liner have to be cut to the right length?
The liner must reach the correct point at both ends of the torch. If it is trimmed too long or too short, the wire can snag or be unsupported, which causes serious feeding problems.
The correct amount of liner to leave protruding or to trim back is given in the maker's instructions for your torch, and many makers supply a gauge or marks to help. Follow those, and do not guess the length.